diff() for differences in Pandas - Mini Project: Build & Apply

Calculate Differences Using diff() in pandas

📖 Scenario: You work in a small shop that tracks daily sales numbers. You want to see how sales change from one day to the next.

🎯 Goal: Build a small program that uses pandas to find the daily difference in sales numbers using the diff() method.

📋 What You'll Learn

Create a pandas DataFrame with exact sales data for 5 days

Add a variable for the number of periods to calculate difference

Use the diff() method on the sales column with the periods variable

Print the DataFrame showing the original sales and the differences

💡 Why This Matters

🌍 Real World

Businesses often track changes in sales or other metrics day by day to understand trends and make decisions.

💼 Career

Data analysts and scientists use difference calculations to analyze time series data and detect patterns or anomalies.

1

Create the sales DataFrame

Create a pandas DataFrame called sales_data with a column 'Sales' containing these exact values: [100, 120, 115, 130, 125]. Use the index as days from 1 to 5.

Pandas

import pandas as pd
# Create the sales_data DataFrame with 'Sales' column and days 1 to 5 as index
# Your code here

Need a hint?

Use pd.DataFrame with a dictionary for the column and set the index to days 1 through 5.

2

Set the periods variable

Create a variable called periods and set it to 1 to represent the difference between consecutive days.

Pandas

import pandas as pd
sales_data = pd.DataFrame({'Sales': [100, 120, 115, 130, 125]}, index=[1, 2, 3, 4, 5])
# Create the periods variable and set it to 1
# Your code here

Need a hint?

Just create a variable named periods and assign it the value 1.

3

Calculate the daily sales difference

Create a new column in sales_data called 'Difference' by applying the diff() method on the 'Sales' column using the periods variable.

Pandas

import pandas as pd
sales_data = pd.DataFrame({'Sales': [100, 120, 115, 130, 125]}, index=[1, 2, 3, 4, 5])
periods = 1
# Add a 'Difference' column using diff() on 'Sales' with periods
# Your code here

Need a hint?

Use sales_data['Sales'].diff(periods=periods) and assign it to sales_data['Difference'].

4

Print the sales data with differences

Print the sales_data DataFrame to show the original sales and the calculated daily differences.

Pandas

import pandas as pd
sales_data = pd.DataFrame({'Sales': [100, 120, 115, 130, 125]}, index=[1, 2, 3, 4, 5])
periods = 1
sales_data['Difference'] = sales_data['Sales'].diff(periods=periods)
# Print the sales_data DataFrame
# Your code here

Need a hint?

Use print(sales_data) to show the DataFrame with the new column.